As we move through July, we are working toward protecting peanuts from leaf spot disease, southern stem rot, and in the Virginia-Carolina region, Sclerotinia blight. As with most production and pest management practices, look local first to get recommendations that are most appropriate for your area. Certainly, there are some basic principles associated with disease management that transcend borders and geographies, but there is a wealth of information you can use at the local level.

In North Carolina, we make about 5 applications of fungicides per cropping cycle. All sprays are important for leaf spot control while sprays 2, 3, and 4 need effective components that protect peanuts from southern stem rot. We have a lot of options. Our recommendation is to start with chlorothalonil and end with chlorothalonil. Fungicides in between these sprays have strengths and weaknesses. Here are some questions you might ask. Am I behind and do I need something with a degree of curative activity? Can I increase the length of time between sprays because of weather conditions or logistics? What is the status of fungicide resistance or loss of sensitivity of the pathogen to fungicides in my area? How much money do I have to spend? How quickly can I get around to my peanuts for a timely spray? How much do the products I can use cost me? Are there any secondary or induced pests that can arise based on my fungicide use pattern? How much water should I use? Does the fungicide just protect on the leaf surface, or does it move into the leaflet and then translocate within the leaflet? Is okay to mix a few more things like insecticide, herbicide, micronutrient or plant growth regulator with my fungicide? Do I need an adjuvant? What do I do if it rains 2 hours after I spray? How about 4 hours?

There may be more questions to consider beyond these. It can be overwhelming when we consider all the possible questions. One thing that might help at this point is to think about what has been successful in the past. If you get bogged down mentally on the decision, use what has worked in the past with an eye toward thinking about ways to minimize risk even more, both in the short-term and long-term. Two ways to minimize risk are to be timely with whatever you decide to spray over the cropping cycle. Know the limitations of what you decide to use and help the fungicides be successful by spraying all your fungicides on a tightly defined schedule. Secondly, rotate chemistry and consider the curative nature of products if you get behind (I guess that’s three.) If you can do these three things well – make timely sprays, rotate chemistry, and adjust where needed due to logistics or weather – you have a great shot at going into harvest season with a healthy peanut crop and a lot of flexibility for digging.

In North Carolina and Virginia, we have leaf spot and Sclerotinia blight advisories that can help you make decisions on timing of sprays. Using temperature and humidity calculations, advisories provide information on whether fungicide is needed at points in the cropping cycle. This can help us spray less frequently when conditions are not favorable for the pathogen and can help us minimize the chance of flaring spider mites, for example. It can also help us keep spraying even though it may be hot and dry, but dew points are still high enough for disease to progress. In surveys, around 50% of respondents use advisories in their decision-making. They may not use them religiously, but they gain from them as another point of reference.